Sensitive hydraulic tracer valve



44 formed in the end thereof in which is mounted a spring 45 which abuts a cap 4'fitattachedto the valve housing Ill. The spring 45 continuously urges'the member 44 and connected valve meni pressure port 5|: to the line 5! and thereby cause valve groove 54. The housing has an additional pair of ports 55 and 56' which are in constant in the end thereof. The member 42 hasa'soicket communication with the grooves 53 and 54 respectively,.and these ports are connecte dby chanjr-iels l and 58 to the motor lines 2!} and 2| respectively. Each line 51 and 58 has serially arranged therein a resistance 59 which may be in the form of a coil of tubing The valve housing is provided with an exhaust port 60 for connecting the an- ";nular groove 54 to exhaust. It will now be seen ber l l downward as viewed in FigureLli attempt-5:

ing to centralize the ball 4| in the conical sockets and thereby hold the axis'of the tracerinember" parallel to the axis of movement of the valve plunger." i

When the tracer' is i-nengagemefit V pattern'Qthe traceris held by the pattern in a deflected position with" respect toa" "'ertical {axis 41, as; for "instance, inthe angular position indicatedby the axis 48,'and'the parts are so adjusted that there is a defiected'position in-which the valve plunger H "is held in a*neutral=--position which is the-position shown in' Figure ;It should 'now be obv'ioustha-t as the deflection of the tracer is varie'd by the pattern 36-; that it fwould-cau'se' movement of the valve 1unger=lr uporuown, and thereby continuously reverse-tli'e'fiow of pres sure to opposite ends of the cylinder Z2.' **'It;will

be obvious that an upward'm'ovement-bf the tracer valve II by the tracer-from 'thepositiomshown would cause a flow of fluid pressure to the? upper end- 'of' the cylinder "22; and thereby c'ause' the cylinder and valve housing I ll to' Fmov' upward,-

thus following up movement'- of the valve plunger H, and reposition the parts inianeutraliposition again. An automatic control is thusfobtai'ned." "It has been foundthat if the valve 'spoolsfsuch as-thespool 4l"opposite pressure portYlZ 'is' frlna-de the 'same'width as the width of the'portor annular groove it controls a very sharp or sensitive control is obtained because the slightes't movement of the valve plunger in eitheridirection will .e fiect'a difierentiatioif of pressure inthe oppoi'site ends of thecylinder and although it isr des-irable v tohave-a sensitive control yet 'suc hf a" control 4 tends toset up anundesirableoscillation. A ln'order to over'come this oscillation,- the spools are j made slightly wider than. the por tsf whi'ch they-control, This is shown more; particularly in Figure 2 in which the reierence numeralw indicates the valve spooloppositeftheport 30-,arid

willbe noted that the spool ove' laps'iti ieflower .edge "49 of the port groove, the"ov'erlap; being I I i-indicatedbythe referencefn imeral"51].; i

g in other words, the valv'e 'plunger I; asvije A Figure 2; must be moved upward the'am There.-

combination with the valve toestab hfaide firiite new for small movementspi the valve. To, this endithe valve housing is provided'with an'ffa'ddi- 'ti'onal pressure port 51f, irr the form ofanannular .gro'ove,,andthis port {connected as' show the'supply line l3, 7 i

the groove 51 to; either the ,valve' groove53 orlthe lthatffrom I this arrangement a slight upward movement of the valve plunger will connect the a flow to the line 20, or vice versa, a slight downward movement will connect the pressure port 51 s to the line 58, and thereby to the line 2|. However, any'attemptiat oscillation will be'da'mped by the resistances- 59 so that slight upward and downward m'ovements of the valve which'woul'd normall-ytend to' set up oscillation are damped by the resistances.

The resistances are ofsuch a nature that the I rateofcontinuous flow therethrough is-small; and

this is sufficient forvery small movements of the valve; but-should the valve' be given'a sustained movement in either-direction; then additional- 'Th'ere 'lias' thus been =prov'id'edan improved valve mechanism which is sensitive to small move ments to provide a pressiiiegdifierential =in= -the cylinder '22 sufiicient t'o cause small movement's bu't'firi'a su'fiic iently delayed manner 'that violent oscillation will not be setup; This doesnotfint'eri f ere'yvith controlof the -main valve whicl 1:" is

responsive to gr-"eater movements andpnce the combination of a: valve connections are made thereby the =fiuid ma'y flow more freely dueto the'fact that it does 'not 'ha've to'pa'ss throughthe resistances; Thereforej by he c'dmbinationof the-two sets of connec'tions an improved serlsitillevalv mec hat is claimed is; "-l In a sensitive contra combination of a housing 7 v 'secondpressure; port; a valve 'rnembe'r movable "in ."said ous ng having indep ndent means j-io'r ee i l y l' f ulianou l'yflfie e ee 981.011 of id ports, sai'cl'me'aiis being jointly inovabl'ewiths valve membenone of said means being'r'e sp' on'siv e means being? responsive to sustained i wthiewalve' m b r'ijf li ntlally opening the second'por't, sa i g a iii. 4 i, i lse H new :fr mj, t e econd pte uiie fpj'r t o lin {we e a t i pressure ports, a first -pa letsass'ociated with the first pressure port, a second pair of outlets associated with the second pressure port, a valve, slidably mounted in said housing, having means for normally simultaneously closing the respective pressure ports, one of said means being responsive. to incipient movement of the valve member to establish a .fiow connection between the first of said pressure ports and one of said first pair of outlet ports, resistance means connecting said first pair of outlet ports to flow channels, other means on said valve member responsive to sustained movement of the valve member for subsequently connecting said second pressure port to one of the last-named pair of outlet ports, said last-named pair of outlet ports being connected directly to said flow channels.

3. In a sensitivelcontrol valve mechanism, the combination of a valve housing and a valve member movable in said housing, said housing having two ports parallel connected, one directly and the other by resistance means to a first channel, and two more ports parallel connected, one directly and the other by resistance means to a second channel, said valve housing also having two pressure ports and at least one exhaust port, means on the valve normally simultaneously closing the pressure port supplying the resistance connected ports and responsive to incipient movement of the valve for alternatively connecting said resistance connected ports to pressure and exhaust, other means on said valve normally simultaneously closing the other pressure port and responsive to sustained movement of the valve to alternatively connect the pressure port to one or the other of the direct connected ports.

4. In a sensitive control valve mechanism, the combination of a valve housing having a pair of pressure ports, a valve member having spool portions closing said ports when in a central position and movably mounted in said housing to position the edges of the spools to either side of said ports, said housing having two ports parallel connected to a first channel and two ports parallel connected to a second channel, one of each of said two ports being directly connected and the other resistance connected to its respective channel, one of the spool portions being on the valve responsive to incipient movement of the valve to either side of said central position for alternatively connecting one of said pressure ports to one of said resistance connected ports, and the other of said spool portions on said valve being so related to first spool portion that on sustained movement of the valve it will alternatively connect the other pressure port to one or the other of said direct connected ports.

5. In a sensitive control valve mechanism, the combination of a valve housing having two pressure ports formed therein, a valve member slid ably mounted in said housing having a first spool for closing one of said pressure ports, said spool being of the same size as the said one of the pressure ports whereby incipient movement of the valve in either direction will open said one of the pressure ports, a second spool on said valve for closing the other pressure port but being greater in size than the latter pressure port, thus requiring a sustained movement of the valve in either direction to effect opening of said latter port, a first pair of outlet ports for alternatively receiving the flow from the first pressure, a second pair of outlet ports for alternatively receiving the fiow from the other pressure port, said second pair of ports being directly connected to a pair of channels, and resistance means connecting each of the first pair of outlet ports in one of the respective channels.

6. In a sensitive control valve mechanism, the combination of a housing having a pair of pressure inlets, a valve member having spools for simultaneously closing said inlets, one of said spools being the same size as one inlet, and the other spool being larger than the other inlet, said valve housing having two ports parallel connected, one directly and the other through resistance means to a first channel, and two ports parallel connected, one directly and the other through resistance means to a second channel, said resistance connected ports being on opposite sides of the first spool for connection to pressure upon incipient movement of the valve member. said direct connected ports being on opposite sides of the second spool for connection to the second pressure port upon sustained movement of the valve whereby slight reciprocation of the valve is permitted before connection of the second pressure port to a pressure inlet.

'7. A sensitive control mechanism for a machine tocl or the like including a valve housing having a bore to receive a slidable tracer valve element, a valve slidably mounted in the bore of the housing, and a tracer element carried by the housing for movement relative thereto, said tracer element having a portion reactable on the valve for determining the variable incremental positionings thereof, and a hydraulic actuating circuit controllable by the valve including a pres sure supply conduit, the housing having a pair of axially spaced pressure inlet ports coupled with said conduit, an exhaust conduit, the housing having a first exhaust port intervening the spaced pressure inlet ports and coupled with said exhaust conduit, additional exhaust ports opening into the bore at points axially remote as respects the pressure inlet ports, the valve having a pair of pressure port inlet control spools spaced to register with the respective pressure inlet ports when the valve is in an intermediate position, one of said spools being of substantially the same width as its registering inlet port and the other of said spools having a width slightly in excess of that of its registering inlet port, a first pair of work conduit ports formed in the housing in spanning relation to one of the pres sure ports and a second pair of work conduit ports formed in the housing in spanning relation to the other of said pressure inlet ports, conduit means coupling one work conduit port of each pair with a respective work conduit port of the other pair, and resistance means in each of the conduits from the ports spanning the first pressure inlet port to retard of pressure medium in either direction through said conduits.

WENDELL I. EVANS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,959,178 Sassen May 15, 1934 2,157,240 Keel May 9, 1939 2,241.07? Thoma May 6, 1941 2,332,533 Roehm Oct. 26, 1943 2,365,748 Curtis Dec. 26, 1944 

